Course:KIN366/ConceptLibrary/Critical Periods of Development
|Movement Experiences for Children|
|Instructor:||Dr. Shannon S.D. Bredin|
|Important Course Pages|
- 1 Critical Periods of Development
- 2 Neurological Processes & Perspectives on Early Brain Development
- 3 Experiments
- 4 Critical Periods of Motor Development
- 5 Windows of Achievement for Motor Milestone
- 6 Closure of Critical Period
- 7 Implications & Recommendations for Educators and Parents
- 8 Critiques
- 9 Practical Application
- 10 References
Critical Periods of Development
The critical periods of development refers to the sensitive period of brain plasticity in which brain circuits are extremely susceptible to the acquisition of various kinds of information or skills (Hensch, 2004). The time windows are indicative that a child requires a nurturing environment and exposure to external stimulations for optimal brain development (Hensch, 2004). Early stimulations through movement and sensory experiences are primal for lifelong learning as these are the key factors that shape the brain and produce the foundations for development (Gale et al., 2003). In other words, the critical periods represent certain ‘windows of opportunity’, where experience is deemed to have the greatest effect for the acquisition of language, feelings, vision, and especially developing motor control (Hensch, 2004). The important feature of critical periods is that the period of plasticity will gradually reduce and narrow, emphasizing the importance of early positive experiences to achieve full potential for functionality (Gale et al., 2003). This period of quick learning illustrates why parents enroll their children in a diverse spectrum of classes and activities at an early age for achieving long-term results.
Neurological Processes & Perspectives on Early Brain Development
Developmental Plasticity and Formation of Neural Circuitry
The critical period of development outlines the time range where the postnatal nervous system rapidly acquire and store information induced by external factors (Chugani, 1998). Early brain development is profoundly dependent on neurological processes leading to developmental plasticity, or the modifications of neural connections as a result of learning by experience and environmental interactions (Gabbard, 1998). Predominantly, neural circuitry is the structural organization or the ‘wiring’ connection between neurons that intrinsically allow basic functions of human behavior to exist (Gabbard, 1998). Past researchers have determined that an individual has preprogrammed wiring of neural circuitry solely influenced by genetic blueprints (Gabbard, 1998). However, contemporary perspectives delineate that not all circuits are prewired, implying that the remainder connections are dependent upon experiences from external stimulus during the early years (Chugani, 1998). Contemporary researchers have discovered that the main circuits responsible for controlling heart beat and involuntary behavior of the brain are still determined by genetics, but stimulation produces the remaining connections that shape the brain (Gabbard, 1998). Movement experiences or any type of activity will trigger certain corresponding synapses and are continually strengthened through activation or excitement. It is imperative to understand that stimulation is the significant factor that allows for the integration of neurons into the circuitry, exemplifying how brain development is activity dependent (Gabbard, 1998).
Synaptic Overgrowth And Synaptic Pruning
Comparatively, a child house 50-100% more synapse connections in the brain than an average adult but will lose half the amount of neuronal connections at the end of the critical period (Chechik et al, 1999). The growth of the human brain is dependent on the orderly process of synaptic overgrowth followed by selective pruning of weak, unused or inactive neurons (Chechik et al, 1998). The elimination of synapses serves a regulatory role in brain development by reducing the interference of erroneous synapse to maximize performance (Chechik et al, 1998). Synaptic overgrowth and synaptic pruning contributes to the overall growth of the human brain (Chechik et al, 1998). The brain develops complexity and continually modifies itself by the influence of the quality and quantity of experience received (Low & Cheng, 2006).
Researchers have speculated the effects of different environmental settings on human development, but have only been able to confirm their theories using animal tests. In a study done by Sirevaag and Greenough (1987), rats were raised in 3 different environments: complex, social or individual cage. Rats assigned to complex environments were individually raised in a wire cage supplied with wooden toys and given the 30 minutes of daily exposure to a larger area with more toys. In social environments, 2 rats would inhabit a single cage without the presence of any toys. Lastly, selective rats would be placed in the individual cage, which is equivalent to solidary confinement.
After 30 days of comparison, results delineate that rats raised in complex settings developed more synapses per neuron than rats raised in individual cages (Sirevaag & Greenough, 1987). This supports the theory that enriched settings involving numerous environmental stimuli greatly contribute to brain development as compared to deprived or disadvantaged environments (Gabbard, 1998). The same general effect should be expected for children who are exposed to environments characterized by movement and learning experiences (Gabbard, 1998).
Critical Periods of Motor Development
According to Newell (1991), early movement experiences of children within the critical period and acquisition of actions and movement dynamics improve long-term performance.
Prenatal to 5 years of age
Although the time range from prenatal to 5 years represent continued development, the first 2 years of childhood is the dynamic period of gross motor development (Gabbard, 1998). The development of gross motor skills enables a child to move independently and perform meaningful interactions with the surrounding environment (Higgins, 1991). During this sensitive period, children will typically acquire postural control and general movements that vitalizes proprioceptive sense (Higgins, 1991). This suggests that physical activity may be a significant factor in the early development of motor control.
Postnatal to 9 years of age
Following gross motor development, acquisition of fine motor control is emphasized from postnatal to 9 years of age (Gabbard, 1998). Fine motor control utilizes smaller movements from hands, wrist, fingers, and feet that work to provide actions requiring coordination, such as picking up objects (Newell, 1991). The window of opportunity for fine motor control is extended far beyond gross motor skills for continued development of dexterity (Newell, 1991).
10 years of age
The speculated age that estimates the closure of window for most behavior functions is around 10 years of age where brain plasticity is reduced and synaptic connectivity is slowed (Gabbard, 1998).
Windows of Achievement for Motor Milestone
The following list approximates the time frame for the achievement of 6 gross motor milestones during the crucial first 2 years of life (WHO, 2006).
- 4- 9 months: Sitting without support
- 5- 11 months: Standing with assistance
- 5- 13 months: Hands & knees crawling
- 6- 14 months: Walking with assistance
- 7- 17 months: Standing alone
- 8- 18 months: Walking alone
Again, this emphasizes the importance of giving children the opportunity to practice and learn from experience. The critical periods of development outlines major motor milestone achievement times indicative of a child’s developmental status (WHO, 2006). Children that achieve motor milestones outside of corresponding windows could raise red flags of delayed development (WHO, 2006).
Closure of Critical Period
The window of opportunity exists for an unprecedented period of time where performance and learning are extensively maximized (Hensch, 2004). Experience is vital to laying down the foundation dedicated to acquiring skills necessary for development. However, if experiences are procured outside of the window, the results are minimized or could have no lasting effect for future purposes (Hensch, 2004). At the closure of critical periods (10 years old), brain plasticity is narrowed but not completely diminished (Gabbard, 1998). This just means that the level of efficiency in acquiring motor skills, language, feelings, and any kind of stimulus is significantly reduced. Generally, performance optimization will be at risk but severity of the case would lead to developmental impairment (Hensch, 2004).
Implications & Recommendations for Educators and Parents
The identification of phases during early childhood associated with enhanced learning and heightened levels of brain plasticity provides crucial implication that movement experiences must be available for a child to achieve optimal development. First, movement experiences should be introduced in the early years of life and within the described time window. Second, cooperative efforts between parents, teachers and educators are necessary for maximal benefits. The following recommendations suggest activities parents should encourage their children to execute with the goals of enhancing motor skill development within the critical period.
1. Basic Gross Motor Activities
Children must be exposed to learning enriched settings that highlight the importance of acquiring basic gross motor skills primitive for normal functioning during the critical period (Higgins, 1991). Activities that utilize movements of large muscles such as running, walking, kicking, jumping, and climbing will stimulate new wiring patterns in the brain benefiting long-term retention (Newell, 1991). Repeated executions of these gross motor movements accelerate acquisition and foster better strength, coordination, locomotion and postural control (Newell, 1991).
2. Sensory-motor Activities
Parents are recommended to provide opportunities for children to obtain positive sensory-motor experiences through activities requiring visual, fine and gross motor movements (Newell, 1991). Emphasis on hand-eye coordination activities such as reaching to grab, bouncing balls, throwing and catching stimulate visual, tactile and kinesthetic awareness (Newell, 1991). Building blocks, puzzle, stringing beads and certain kinds of toys using manipulation techniques and precision also support sensory-motor development (Newell, 1991).
One major critique behind the theory of critical period of development is the lack of transferability of animal studies with humans due to ethical concerns (Bailey, 2002). The validity of researches is based on animal testing such as the one previously mentioned above.
Understanding the critical periods of children’s development provides continued learning of the complexity of the human brain. Gaining insight into the underlying processes of brain development in accordance with movement and sensory experiences will foster new strategies for therapy as well as identifying the possibility of extending critical periods for lifelong learning.
- Bailey, D. B. (2002). Are critical periods critical for early childhood education?: The role of timing in early childhood pedagogy. Early childhood research quarterly, 17(3): 281-294. doi: 10.1016/S0885-2006(02)00165-5
- Chechik, G., Meilijson, I., & Ruppin, E. (1998). Synaptic pruning in development: a computational account. Neural Computation, 10: 1759-1777. Retrieved from: http://www.mitpressjournals.org.ezproxy.library.ubc.ca/doi/pdf/10.1162/089976698300017124
- Chechik, G., Meilijson, I., & Ruppin, E. (1999). Neuronal regulation: a mechanism for synaptic pruning during brain maturation. Neural Computation, 11: 2061-2080. Retrieved from: http://www.mitpressjournals.org.ezproxy.library.ubc.ca/doi/pdf/10.1162/089976699300016089
- Chugani, H.T. (1998). A critical period of brain development: Studies of cerebral glucose utilization with PET. Preventive Medicine, 27, 184-188. Retrieved from: http://neur2201.unsw.wikispaces.net/file/view/critical+period.pdf
- Gabbard, C. (1998). Windows of opportunity for early brain and motor development. Jounral of Physical Education, Recreation & Dance, 69, 54-55. doi: 10.1080/07303084.1998.10605614
- Gale, C.R., O’Callaghan, F.J., Godfrey, K.M., Law, C.M., & Martyn, C.N. (2003). Critical periods of brain growth and cognitive function in children. A Journal of Neurology, 1: 321-239. Retrieved from: http://brain.oxfordjournals.org/content/brain/127/2/321.full.pdf
- Hensch, T.K. (2004). Critical period regulation. Annual Review of Neuroscience, 27: 549-579. doi: 10.1146/annurev.neuro.27.070203.144327
- Higgins, S. (1991). Motor skill acquisition. Physical Therapy, 71: 123- 139. Retrieved from: http://www.physther.net/content/71/2/123.full.pdf
- Low, LK. & Cheng, HJ. (2006). "Axon pruning: an essential step underlying the developmental plasticity of neuronal connections". Philos Trans R Soc Lond B Biol Sci 361: 1531–1544. doi:10.1098/rstb.2006.1883.
- Newell, K.M. (1991). Motor skill acquisition. Annual Review of Psychology, 42: 213- 237. Retrieved from: http://neur2201.unsw.wikispaces.net/file/view/critical+period.pdf
- Newport, E.L., Bavelier, D., & Neville, H.J. (2001). Critical thinking about critical periods: perspectives on a critical period for language acquisition. Language, Brain, and Cognitive Development, 1: 481-502. Retrieved from: http://www.bcs.rochester.edu/people/newport/pdf/Newport_Bav_Nev01.pdf
- Sirevaag, A.M., & Greenough, W.T. (1987). Differential rearing effects on rat visual cortex synapses. III. Neuronal and glial nuclei, boutons, dendrites, and capillaries. Brain research, 424, 320-332. Retrived from: http://ac.els-cdn.com.ezproxy.library.ubc.ca/0006899387914776/1-s2.0-0006899387914776-main.pdf?_tid=a63257b0-bfa1-11e4-8aaa-00000aab0f6c&acdnat=1425166352_6432a707a11e477b6371f5f95c60483c
- World Health Organization (2006). WHO Motor Development Study: Windows of achievement for six gross motor development milestones. Acta Paediatrica, 450: 86-95. DOI: 10.1080/08035320500495563